Power directional system



Feb. 13, 1934.

E. R. EVANS POWER DIRECTIONAL SYSTEM Filed Feb. 15. 1930 FHA 85 R0 Patented Feb. 13, 1934 1,941,289 rowan nmac'rromr. srsmr Earl R. Evans, Washington, D. 0. Application February 15, 1930. Serial No. 428,810

6 Claims.

My invention relates to electrical power distribution systems and particularly to systems of this character embodying electrical space discharge devices responsive to a reversal of power 5 in a circuit or operative to control or regulate a circuit upon a reverslg l of power therein.

One object of my ention is to provide an improved electrical system embodying a space discharge device of controllable impedance, such l6 as an electric discharge valve operating with 26 ternal voltage drop so that it is adapted to operate with high efiiciency on ordinary low-voltage power circuits.

When an alternating potential of relatively low frequency is applied to the cathode and anode 23 of the Langmuir tube the average value of the space current through the device depends upon the magnitude and, in some instances, the phase relation of the potential on the control electrode. The detailed construction and theory of opera 0 tion of the tube are set forth in the abovementioned patent. Accordingly, this specific tube or valve, which is of the discontinuous control type is referred to herein although the detailed construction of the arc-discharge device 35 may be modified, as the object of my invention, in. general terms, is to proyide a system embodying a device of this general character which is responsive to or rendered operative upon the reversal of the flow of power in a circuit to control 4 or regulate said circuit or an associated circuit. Another object of my invention is to provide improved means for preventing or limiting the reversal of power in an electrical circuit.

Another object of my invention is to provide means of this character which does not require the use of the usual wattmeter or reverse-energy relays. j

A still further object of my invention is to provide a system having an inherent reverse-energy impedance operating without the time lag which characterizes the prior protective systems employing reverse-energy relays.

Other objects and advantages of my invention will appear from the following detailed description of the embodiments thereof shown on the attached drawing, wherein Fig. 1 is a diagrammatic view of an electrical system including a circuit-breaker controlled by a space-discharge device, and

Fig. 2 is a similar view of a modification in which the space-discharge device is connected in the distribution circuit.

Referring to the drawing, the system shown in Fig. 1 comprises an alternating-current line or distribution circuit 1, a circuit-interrupter 2 therein provided with a trip coil 3 and controlled by an arc" discharge device 4. For the purposes of illustration, the device 4 is shown as a tube having a hot cathode 5, a grid or control electrode 6 and an anode 7, the construction and arrangement of the electrode 6 and the pressure of the gas-filling in the tube being such that the average current through the tube depends upon the potential of the control electrode. For example, the device 4 may be a power-arc tube of the type disclosed in the above-mentioned Langmuir patent.

A current transformer 10 in the line circuit is connected to the cathode and anode of the arc discharge device 4. .The potential of the control electrode 6 relative to the cathode 5 is determined by a potential transformer llconnected across the circuit 1. The cathode 5 and control electrode 6 are connected to the secondary winding of the transformer 11, a phase rotator 12 being arranged if desired to insure the proper phase relation of control electrode potential to the line current under normal conditions. A resistor 13 may be provided to limit the control electrode current.

In operation, the current flowing in the line circult, through the current transformer 10, produces an alternating potential between the cathode 5 and the anode 7 of the arc discharge device4. Similarly, an alternating potential is produced between the cathode 5 and the control electrode 8 by the transformer 11.

When the anode 7 is at'a positive potential with respect to the cathode 5, an arc will be-established in the discharge valve 4 at a relatively low potential difference provided the potential of the control electrode is at substantially the same potential as the cathode or is more positive. Under normal conditions, however, when the flow of power is in the desired direction, the potential of the control electrode is negative when the anode is positive with respect to the cathode. Hence the average value of the current traversing the arcdischarge device 4 is insumcient to energize the tor a considerable variation in the power rector of the circuit 1.

Upon a predetermined change in the phase relation of the current and voltage circuit 1, such as that produced by a reversal otthe iiow of power in the circuit, the control electrode 6 is no longer eflective' to limit the current through the arc-discharge device 4 to a low value and the trip coil 3 is ei ergized'thereby opening the ,circuitl.

In-the modification shown in Fig. 2, the arcdischarge device is arranged to carry'the' line current and to control the same by its change in impedance upon a predetermined change in the phase relation between the current'and voltage in the circuit. In this embodiment of the inven-.

tion, a circuit is provided wlth'two arc-discharge valves 21 and 22 oppositely arranged to permit an alternating current to flow. in the cir- 20 cuit under normal conditions. The tube 21' comprises a cathode 23, control electrode 24 and anode 25. The tube 22 comprises a cathode 26. control electrode 27 and anode 28. The potentials of the control electrodes 27 and 24 are controlled by potential transformers 29 and30,respectively,connected to the circuit 20. Resistors 31 and 32 may be provided to limit the current traversing the control-electrode circuit.

In this modification, the arc-discharge devices 21 and 22 normally present substantially no impedance to the line current. Upon a reversal of the ilow of power in the circuit or other predetermined change in the phase relation between current and voltage, the phase relations or the alterhating potentials upon the control electrodes 24 and 2'1 shift in such a manner as to increase the impedance of the devices 21 and 22 and thereby limit the current flowing in the distribution circuit.

Various modifications may be made in the systems disclosed without departing from the scope otthe invention, which is indicated in the appended claims.

Iclaim:

1. An alternating-current electric system comprising a distribution circuit. an arc-discharge device embodying a cathode, an anode and a control electrode, the cathode-anode circuit 01 said device being connected directly in series in said circuit, and means for app yi to said control electrode an alternating potential which has atalltimesasubstantiallyconstantphaserela-- tion to the voltage across saidcircuit whereby the impedance oi said arc-discharge device dependsuponthe directionoitheflawoienergyin said circuit. .1

2. 11; combination, an alternating current electric circuit, electric discharge valve means for controlling the impedance of said circuit, having an anode, a cathode and a control electrode, the

,o47,seo trip coil 3 and open the circuit-interrupter 2 even cathode-anode circuit od ssid valve means being connected directlyin'series in said circuit and means for energizing said control electrode in accordance with thephase relation between the current and the voltage oi the circuit to varythe conductivity of said valve means.

8. In combination, an alternating current electric circuit, a'pair of electric discharge valvesior impedance 0! said circuit, each oI-said valves having ananode a cathode ands control electrode, the cathode-anode circuits at saidvalves being oppositely connected directly in series in said circuit to permit an alternating current to flow therein under normal conditions and means for energizing the control ,electrodesgot, said valves to vary the impedance thereof in accordance'with the direction of energy flow in the circuit. 1

4. In combination, an alternating current electric circuit, a pair 01 electric valves oi the dis; continuous control type for controlling the impedance or said circuit, each valve having an anode, a cathode and a control electrode, the cathode-anode circuits of said valves being oppositely connected directly in series with said circuit to permit an alternating current to flow therein under normal conditions, and means Ior energizing the control electrodes oi. said valves to vary the conductivity thereoi in accordance with the direction oieenergy flow in the circuit.

5. Incombination with an alternating current electric circuit, a pair of electric discharge valves for controlling the impedance of said circuit, each or said valves having an anode. a cathode and a control electrode, the cathode-anode circuits of said valves being oppositely connected directly in series with said circuit to permit an alternating current to flow therein under normal conditions and the cathode-control electrode circuits oi said valves being connected to be energized in dependence on the voltage-oi. the circuit to control the-conductivity oi the valves in accordance with the direction oi, energy flow in the circuit.

6. An alternating current electric system comprising a distribution circuit, an arc-discharge de-' 190 vice embodying a cathode, an anode and a' control electrode, a cathode-anode circuit and the cathode-control-electrode circuit 0! said arc-dis charge device being connected respectively directly in series with and in parallel relation to said circuit for energization in accordance with alternating potentials displaced in phase substantially in accordance with the phase displacement between the alternating current and voltage of the distribution circuit under either normal m or reverse power flow therein whereby the conductivity of said arc-discharge device depends upon the direction or the flow oi energy in said circuit.

EARL R. EVANS. m 

